1. Field of the Invention
The present invention relates to wire-wound coils including pairs of wound windings and methods for manufacturing wire-wound coils.
2. Description of the Related Art
A known wire-wound coil includes a core member including a columnar core portion and a pair of collar portions formed at either end of the core portion, a pair of wires including a primary coil and a secondary coil wound around the surface of the core portion, and electrode portions, to which the ends of the coils are electrically connected, formed on the pair of collar portions. The primary coil and the secondary coil in the same winding turn are wound around the surface of the core portion so as to be separated from each other (See Japanese Unexamined Patent Application Publication No. 2004-146671).
Since the above-described wire-wound coil has the wires wound around the planar surface of the core portion and does not have any means for positioning the wires, the wires move over the surface of the core portion in some cases. Further, when the wires move over the surface of the core portion, the characteristic impedance of the coil in correlation with the distance between the wires cannot be flexibly adjusted.
Moreover, since the separation of a pair of adjacent wires causes variations in the electrostatic capacitance between the wires, the characteristic impedance of the coil may vary widely depending on variations in the winding of the wires.